A Study Investigating the Relationship Between the Development of Laronidase Antibody and Urinary GAG (Glycosaminoglycan) Levels in Aldurazyme® Treated Patients

Inclusion Criteria: Have a documented diagnosis of MPS I confirmed by measurable signs and symptoms and deficient α-L-iduronidase activity (<10% of the lower limit of normal). For a patients receiving Aldurazyme therapy prior to study entry: Have available as baseline data the results of urinary GAG levels and IgG antibody titers collected prior to the patient's first Aldurazyme infusion. Provide signed, written informed consent prior to any protocol-related procedures being performed. Consent of a legally authorized guardian(s) is (are) required for patients under 18 years. Exclusion Criteria: Have previously received Aldurazyme without the collection of baseline samples as specified. Have a suspected hypersensitivity to Aldurazyme or a know hypersensitivity to components of infusion solution. Have received a Hematopoietic Stem Cell Transplantation, injection fibroblast therapy, or major organ transplant. Are receiving chronic immunosuppressant therapy. Have a medical condition, serious intercurrent illness, or other extenuating circumstances that may interfere with study compliance including all prescribed evaluations and follow-up activities. Are pregnant or lactating Have received investigational drug within 30 days prior to study enrollment